Question

All of the following swellings are transilluminant, EXCEPT:

• A. Meningocoele
• B. Hydrocoele
• C. Thyroglossal cyst
• D. Lipoma

Hint:

Think about which of these four swellings is a solid mass rather than a fluid-filled sac.

Answer 1

The Correct Option is D

Step 1: Understanding the Question:
The question is asking which of four surgical swellings does NOT light up when a torch is held against it in a dark room, that is, which one fails the transillumination test.

Step 2: Key Concept or Approach:
Transillumination is a bedside clinical test used to separate cystic, fluid- or gas-filled swellings from solid ones. Light passes through a swelling that contains clear fluid or a thin translucent wall, producing a visible glow around the torch. A solid mass simply blocks the light, so it does not transilluminate.

Step 3: Working Through the Options:
Meningocoele is a sac herniating through a spinal or cranial defect that contains clear cerebrospinal fluid, so it transilluminates well. Hydrocoele is a collection of clear serous fluid around the testis within the tunica vaginalis and is the classic example of a brilliantly transilluminant swelling. Thyroglossal cyst is a thin-walled midline cystic swelling containing clear mucoid fluid, and it also transilluminates. Lipoma, in contrast, is a solid encapsulated mass of mature fat cells with no fluid cavity, so light cannot pass through it and it stays dark on testing.

Step 4: Conclusion:
Because it is a solid fatty tumour rather than a fluid-filled sac, Lipoma is the swelling that does not transilluminate, making it the correct answer.